The Pliocene Shelburne Mass-Movement and Consequent Tsunami, Western Scotian Slope
Submarine mass-movement is a significant process along continental margins, even along passive margin slopes. Interpretation of seismic reflection profiles along the Scotian margin, for example, indicates the Cenozoic section is dominated by mass transport deposits (MTD) at a spectrum of scales. Occasional exceptionally large MTDs are observed which seem particularly foreign in a passive continental margin setting. The Shelburne MTD was recognized from exploration industry seismic reflection data along the western Scotian Slope. It is a buried Plio/ Pleistocene feature that extends in excess of 100 km from the upper slope to the abyssal plain and maps to an area in excess of 5,990 km2 and a volume >862 km3. Its features demonstrate that it is a frontally-emergent MTD with a slump portion and a debris flow/run-out portion. Tsunami simulations were generated for this event, one assuming the slump portion generated the tsunami, the other, both the slump and debris flow contributed. For a mass movement comparable in scale to the Shelburne MTD, these simulations demonstrate that the city of Halifax, Nova Scotia, would be impacted within 70 to 80 minutes by a 13–25 m high wave, depending on the MTD source volume (slump or slump and debris field).
KeywordsSubmarine landslide mass-failure mass-transport deposit tsunami geohazard seismic reflection
The authors would like to express their appreciation to TGS-Nopec for permitting use of the seismic data and to D.C. Campbell and S. Bartel for assistance with interpretation and technical issues. This work was conducted under the NRCan Geoscience for Ocean Management Program. We also thank the reviewers Drs. K. Moran and A. Zakeri for critiquing and improving this manuscript.
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